The present invention relates to a coated solid medicament form having releasability of the active ingredient only in the large intestine or, more particularly, to a coated solid medicament form which, when orally administrated, passes unaffected through the stomach and small intestine but is disintegrated when it reaches the large intestine so as to release the therapeutically active ingredient contained therein only in the large intestine.
It is eagerly desired in recent years to develop a solid medicament form capable of releasing the active ingredient only in the large intestine when it is orally administrated in view of the increasing trend of various diseases of the large intestine such as ulcerative colitis and the like, for which diseases oral administration of a medicament can be an efficient therapeutic means, and in view of the fact that certain medicinal compounds such as insulin used for the therapeutic treatment of diabetes, which hitherto cannot be orally administrated due to decomposition and deactivation by digestive enzymes such as peptidase in the digestive organ, should desirably be rendered adaptable to oral administration.
With an object mentioned above, a proposal is made in "Fine Chemicals", Nov. 1, 1989 issue, to prepare a coated solid medicament form by using a specific polyurethane degradable in the large intestine. In this coated solid medicament form, the biodegradability of the specific polyurethane is utilized under the influences of the bacteria inhabiting in the large intestine to cause disintegration of the solid medicament form in the large intestine. An important problem here is, since polyurethane is a totally synthetic substance, to ensure that absolutely no adverse effect such as toxicity is exhibited against the human body by the product produced by the decomposition of the polyurethane in the large intestine.
Standing on a guide principle that the above mentioned problem due to the decomposition product of the coating material produced in the large intestine could be mostly solved by using a coating material of natural origin, the inventors have conducted extensive investigations to develop a novel coating on a solid medicament form by utilizing a coating material of natural origin, optionally, in combination with another coating material, which may not be of a natural origin, hardly decomposable in the digestive canals to be freed from the problem of toxicity or any adverse influences against human health.